Lesson: Metabolism and Glucose Homeostasis

absorptive/postprandial state

• injested nutrients from GI tract enter blood

• ~4 hour duration after meal

• available nutrients used for energy, maintenance, with extra stored for later

postabsorptive/fasted state

• after absorptive state, GI tract contains no nutrients

  • energy required during absorptive state and prior energy stores now provide energy

absorptive/fed pathways

• body rebuilds, stores energy for later

• lots of -genesis (creating) names

• glycogenesis

• lipogenesis

glycogenesis

• glycogen synthesis

• liver (~100 g)

• Muscle (~500 g)

lipogenesis

• in adipose and liver

• fats

• small amt of proteins

• (not just for glucose)

what is used for energy during the absorptive state?

muscle protein

some amino acids are synthesized into…

post absorptive pathways

• body maintains blood glucose and other energy production

• more -lysis or breaking apart pathways

• lipolysis

• glycogenolysis

• gluconeogenesis

what are the -lysis pathways in post absorptive pathways?

glucogeneogenesis

• produces “new” glucose from lactate, amino acids, glycerol

• (not all amino acids used for this, but some are)

• primarily in live (some in kidneys)

red blood

• cannot use ketone bodies (no mitochondria)

• must use glucose

absorptive state

• actions of insulin

post absorptive state

• actions of low insulin

fasted state

• net export of glucose

• fatty acids into blood for delivery to tissues

fed state

• net uptake of nutrients from blood to use or store in tissues

insulin

fasted and fed states are processes mediated by:

endocrine pancreatic B cells

what cells produce insulin?

reducing blood glucose

what occurs when insulin prompts many tissues to uptake insulin?

• for triglyceride synthesis

  • lipogenesis/ fat storage

why do adipocytes uptake glucose?

insulin nutrient effects

• GLUT4 translocation to cell membrane, cells uptake glucose

• amino acid uptake by muscle

• adipose tissue fatty acid synthesis

glucagon

what do endocrine pancreatic beta cells produce?

• glucagon raises blood glucose

what is the antagonistic (opposing) effect to insulin?

pancreas

where does insulin come from?

anabolic

what is insulin considered as a hormone?

increase of plasma insulin to the muscles:

• up glucose uptake and utilization

• net glycogen synthesis

• net amino acid uptake

• net protein synthesis

increase of plasma insulin in adipocytes:

• up glucose uptake and utilization

• net triglyceride synthesis

increase of plasma insulin in the liver:

• down gluconeogenesis

• net glycogen synthesis

• net triglyceride synthesis

• no ketone synthesis

decrease of plasma insulin in muscles:

• down glucose uptake and utilization

• net glycogen catabolism

• net protein catabolism

• net amino acid release

• fatty acid uptake and utilization

decrease of plasma insulin in adipocytes:

• down glucose uptake and utilization

• net triglyceride catabolism and release of glycerol and fatty acids

decrease of plasma insulin in the liver:

• up glucose release due to removal of inhibitory effects on glycogen catabolism and gluconeogenesis

• up ketone synthesis and release

already have glucose available

the liver has net glycogenosis because you…?

net effect

what is it considered when glucose gets out of the bloodstream and into tissues?

insulin regulated by:

• blood glucose

• plasma amino acids

• incretins (amplify insulin response to glucose)

• autonomic activity

• glucose

• fatty acids

what are made more available with sympathetic stimulation via catabolic pathways?

• directly via sympathetic stimulation

• indirectly via catecholamines released by the adrenal medulla

how is glucose and fatty acids made more available with sympathetic stimulation via catabolic pathways?

skeletal muscle contraction

what stimulates GLUT4 translocation independent of insulin?

exercise

what is important for diabetics?

hormonal relationship

this occurs between sympathetic nervous system activation and how it decreases insulin secretion by the pancreas?

more

do you want more or less glucose in your blood so it gets to muscles?

• adipocytes

• liver

• muscle

insulin lowers blood glucose by stimulating these 3 things to uptake glucose?